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AssigneeMitsubishi Rayon Co., Ltd.
InventorsKenichi Sakunaga, Hiroshi Terada, Takashi Yamamoto, Yasuteru Tahara
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A process for the preparation of a multifilament optical fiber having 1,000 to 10,000 islands as optical filaments, which comprises using a composite spinning spinneret for the preparation of an islands-in-a-sea type multifilament fiber, which comprises at least three piled orifice plates including an orifice plate having many island-forming nozzle holes, an orifice plate having a sea-forming nozzle hole and an orifice plate having a filament-gathering nozzle hole, the nozzle hole of the orifice plate arranged just above the lowermost orifice plate having a trumpet-shaped opening extending toward the lower end face thereof and a sea component flow passage being formed between two orifice plates arranged just above the lowermost orifice plate, and supplying a thermoplastic polymer for forming cores of optical filaments from the island-forming nozzle holes and a sea-forming thermoplastic polymer from the sea-forming nozzle hole to effect composite spinning and gathering many filaments in the gathering nozzle hole.
A process for the preparation of an islands-in-a-sea type multifilament optical fiber having 1,000 to 10,000 islands as optical filaments, which comprises using a composite spinning spinneret for the preparation of an islands-in-a-sea type multifilament fiber, which comprises four piled orifice plates consisting of an being arranged in the order of an uppermost core-forming orifice plate having many core-forming nozzle holes, a sheath-forming orifice plate having many sheath-forming nozzle holes, a sea-forming orifice plate having many sea-forming nozzle holes and a lowermost optical filaments-gathering orifice plate having a gatering hole, the nozzle holes of the sea-forming orifice plate having a trumpet-shaped opening extending toward the lower end face thereof and a sea component flow passage being formed between the sheath- and sea-forming orifice plates, and supplying a thermoplastic polymer for forming the cores of the optical filaments from the core-forming nozzle holes, a thermoplastic polymer for forming the sheathes of the optical filaments from the sheath-forming nozzle holes and a sea-forming thermoplastic polymer from the sea-forming nozzle holes to effect and composite spinning and gathering of many filaments in the gathering hole.
A process for the preparation of an islands-in-a-sea type multifilament optical fiber, which comprises using a composite spinning spinneret for the preparation of an islands-in-a-sea type multifilament fiber, which comprises four piled orifice plates consisting of and arranged in the order of an uppermost core-forming orifice plate having many core-forming nozzle holes, a sheath-forming orifice plate having many sheath-forming nozzle holes, a sea-forming orifice plate having many sea-forming nozzle holes and a lowermost optical filaaments-gathering orifice plate having a gathering hole, the nozzle holes of the sea-forming orifice plate having a trumpet-shaped opening extending toward the lower end face thereof and a sea component flow passage being formed between the sheath-and sea-forming orifice plates, and supplying a thermoplastic polymer for forming the cores of the optical filaments for the core-forming nozzle holes, a thermoplastic polymer for forming the sheathes of the optical filaments from the sheath-forming nozzle holes and a sea-forming thermoplastic polymer from the sea-forming nozzle holes to effect a composite spinning and gathering of many filaments in the gathering hole, wherein composite spinning is carried out while selecting resins so that the melt flow rate [MFR].sub.2 of the sea-forming thermoplastic resin, the melt flow rate [MFR].sub.1 of the core-forming thermoplastic resin and the melt flow rate [MFR].sub.3 of the sheath-forming thermoplastic resin satisfy the following requirement:
Dependencies are inferred from the claim text.